page_title: Design of plastic components
section_title: Draft angles
hierarchical_section_title: Design of plastic components / Geometric considerations / Draft angles
caption_attribution_description: English: The profile view of a drafted cylinder, showing the draft dimension.
context_page_description: Injection molding has been one of the most popular ways for fabricating plastic parts for a very long time. They are used in automotive interior parts, electronic housings, housewares, medical equipment, compact discs, and even doghouses. Below are certain rule based standard guidelines which can be referred to while designing parts for injection molding considering manufacturability in mind.
context_section_description: Draft angle design is an important factor when designing plastic parts. Because of shrinkage of plastic material, injection molded parts have a tendency to shrink onto a core. This creates higher contact pressure on the core surface and increases friction between the core and the part, thus making ejection of the part from the mold difficult. Hence, draft angles should be designed properly to assist in part ejection. This also reduces cycle time and improves productivity. Draft angles should be used on interior and exterior walls of the part along the pulling direction. 
  The minimum allowable draft angle is harder to quantify. Plastic material suppliers and molders are the authority on what is the lowest acceptable draft. In most instances, 1degree per side will be sufficient, but between 2 degree and 5 degree per side would be preferable. If the design is not compatible with 1 degree, then allow for 0.5 degree on each side. Even a small draft angle, such as 0.25 degree, is preferable to none at all.
caption: Profile view of a drafted cylinder, showing the draft dimension
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